Process and related device for removing by-product on semiconductor processing chamber sidewalls

ABSTRACT

In some embodiments, a method for cleaning a processing chamber is provided. The method may be performed by introducing a processing gas into a processing chamber that has a by-product disposed along sidewalls of the processing chamber. A plasma is generated from the processing gas using a radio frequency signal. A lower electrode is connected to a first electric potential. Concurrently, a bias voltage having a second electric potential is applied to a sidewall electrode to induce ion bombardment of the by-product, in which the second electric potential has a larger magnitude than the first electric potential. The processing gas is evacuated from the processing chamber.

REFERENCE TO RELATED APPLICATION

This Application claims priority to U.S. Provisional Application No. 62/565,673 filed on Sep. 29, 2017, the contents of which are hereby incorporated by reference in their entirety.

BACKGROUND

Semiconductor processing equipment, such as plasma-enhanced chemical vapor deposition (PE-CVD) systems, plasma etching systems, and sputtering systems, are used extensively throughout the production of modern day electronic devices. This semiconductor processing equipment may contain a processing chamber that helps contain the often reactive processes performed by this equipment. Due to these processes, by-products may form on a sidewall of the processing chamber resulting in decreased performance and/or contamination of the equipment, which may result in a decrease in the yield of electronic devices. In an attempt to maintain equipment efficiency and the yield of electronic devices, a cleaning process is often performed to remove the by-product buildup on the sidewall of the processing chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 illustrates a view of some embodiments of a semiconductor processing system capable of implementing a method of the present disclosure for removing by-product that has accumulated on sidewalls of a processing chamber.

FIGS. 2A-2B illustrates a series of views of more detailed embodiments of a semiconductor processing system capable of implementing a method of the present disclosure for removing by-product that has accumulated on sidewalls of a processing chamber.

FIGS. 3A-3G illustrate a series of views of some embodiments of a method for removing by-product that has accumulated on sidewalls of a processing chamber.

FIGS. 4A-4B illustrate a series of views of some more embodiments of a method for removing by-product that has accumulated on sidewalls of a processing chamber.

FIG. 5 illustrates a flowchart of some embodiments of the method for removing by-product that has accumulated on sidewalls of a processing chamber.

DETAILED DESCRIPTION

The present disclosure will now be described with reference to the drawings wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures are not necessarily drawn to scale. It will be appreciated that this detailed description and the corresponding figures do not limit the scope of the present disclosure in any way, and that the detailed description and figures merely provide a few examples to illustrate some ways in which the inventive concepts can manifest themselves.

The present disclosure provides many different embodiments, or examples, for implementing different features of this disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Integrated circuit (IC) technologies are constantly being improved. These improvements typically involve scaling down of geometries to achieve lower fabrication costs, higher device integration density, higher speeds, and better performance. Due to device scaling, the negative effects of sidewall contamination (e.g., contamination of a substrate resulting from unwanted containments being dislodged from a sidewall of a processing chamber and accumulating on a surface of the substrate) occurring in a processing chamber are magnified.

For example, a workpiece may be loaded into a processing chamber of a plasma etching system. The workpiece may comprise a patterned photoresist layer disposed over an inert metal layer (e.g., silver, copper, etc.). The plasma processing system generates a plasma inside the processing chamber to selectively etch the inert metal layer. During this process, non-volatile by-product is generated and often accumulates on sidewalls of the processing chamber. As the workpiece (or subsequent workpieces) undergoes processing in the processing chamber, the plasma will break some of the bonds of the non-volatile by-product disposed on the processing chamber sidewalls causing atoms of the non-volatile by-product to be dislodged from the sidewall. Accordingly, atoms of the non-volatile by-product may accumulate as contaminants on the workpiece disposed inside the processing chamber. The accumulation of non-volatile by-products on the workpiece may result in an improperly functioning integrated circuit on the faulty workpiece. Current waferless auto-clean (WAC) processes are unable to effectively remove this non-volatile by-product from the processing chamber sidewalls due to lack of physical bombardment of the non-volatile by-products. Therefore, a method (and related system) for cleaning a processing chamber that effectively removes non-volatile by-product from processing chamber sidewalls would improve the reliability and cost of ICs by increasing the efficiency of semiconductor processing equipment.

In some embodiments, the present disclosure relates to a method (and related system) for cleaning a processing chamber that effectively removes non-volatile by-product from processing chamber sidewalls. The method comprises performing an etching process on a workpiece within a processing chamber. During the etching process, by-products from the workpiece may be dislodged from the workpiece and adhere to the sidewall of the processing chamber. After the etching process is complete, the workpiece is removed from the processing chamber. After the workpiece is removed from the processing chamber, a processing gas is introduced into the processing chamber and a plasma is generated from the processing gas. Concurrently, a bias voltage is applied to a sidewall electrode to induce ion bombardment of the by-product disposed on the sidewall of the processing chamber. After the by-product has been effectively bombarded, the processing gas and the by-product can be evacuated from the processing chamber. By physically bombarding the by-product, the by-product can be effectively removed from the sidewalls of the processing chamber and evacuated along with the evacuation of the processing gas. Accordingly, because the improved method alters the typical processing chamber cleaning process by applying a bias voltage to a sidewall electrode to induce ion bombardment, the improved method may increase the reliability of ICs and lower the cost of ICs by increasing the efficiency of semiconductor processing equipment.

With reference to FIG. 1, a view of some embodiments of a semiconductor processing system 100 capable of implementing a method of the present disclosure for removing by-product that has accumulated on sidewalls of a processing chamber is provided.

The semiconductor processing system 100 comprises a processing chamber 102 having a first processing chamber sidewall 104 and a second processing chamber sidewall 106. The processing chamber 102 may be, for example, a plasma-enhanced chemical vapor deposition (PE-CVD) chamber. The processing chamber sidewalls 104/106 comprise a conductive material. In some embodiments, the processing chamber 102 may comprise a dielectric layer disposed on sidewalls of the processing chamber 102 that separates an inner chamber from an outer housing of the processing chamber 102.

A lower electrode 108 is disposed within the processing chamber 102. In some embodiments, an electrostatic chuck 110 is also disposed within the processing chamber 102. In some embodiments, the electrostatic chuck 110 comprises the lower electrode 108. In other embodiments, the electrostatic chuck 110 comprises the lower electrode 108 and an electrostatic chuck electrode (not shown). Further, the electrostatic chuck 110 is configured to hold a workpiece 114 throughout various stages of processing the workpiece 114. In some embodiments, the workpiece 114 comprises a metal layer 118 disposed over a substrate 116 and a photoresist layer 120 disposed over the metal layer 118. In some embodiments, the metal layer 118 may be an inert metal, for example, copper, silver, gold, or some other inert metal. Moreover, an electrostatic chuck pedestal 112 may support the lower electrode 108 and the electrostatic chuck 110. In some embodiments, the electrostatic chuck pedestal 112 comprises an electrical insulating material configured to insulate the electrostatic chuck 110 and the lower electrode 108 from the processing chamber sidewalls.

The processing chamber 102 further comprises a processing gas inlet 122 and a processing chamber gas outlet 124. In some embodiments, the processing gas inlet 122 comprises a valve to control the flow of a processing gas 126 into the processing chamber 102, and the processing chamber gas outlet 124 comprises a valve to control the flow of the processing gas 126 out of the processing chamber. Further, in some embodiments, the processing gas inlet 122 and the processing chamber gas outlet 124 allow a pressure inside the processing chamber 102 to be controlled. In some embodiments, the processing chamber gas outlet 124 may be used in conjunction with a vacuum pump to pump the processing chamber 102 down to a vacuum. In other embodiments, the semiconductor processing system 100 comprises a vacuum pump coupled to a separate orifice into the processing chamber 102 that allows the processing chamber to be pumped down to a vacuum.

The semiconductor processing system 100 also comprises a plasma source 125 configured to provide a plasma within the processing chamber 102. In some embodiments the plasma source 125 may comprise a first radio frequency (RF) power generator 127 coupled to an RF antenna 121 that is electrically insulated from the processing chamber sidewalls 104/106 by RF antenna insulators 123. In some embodiments, the RF antenna 121 may comprise two metal electrodes separated by a small distance and may be disposed within the sidewall of the processing chamber 102. This type of RF antenna 121 may be used in a capacitively coupled plasma (CCP) source. In other embodiments, the RF antenna 121 may have a coil-like shape and may be disposed outside the sidewalls of the processing chamber 102. This type of RF antenna 121 may be used in an inductively coupled plasma (ICP) source. In yet other embodiments, the RF antenna 121 may be a sidewall of the processing chamber 102. The first RF power generator 127 is configured to apply a RF signal having an electric potential to the RF antenna 121 to form a plasma 129 from the processing gas 126 inside the processing chamber 102. In some embodiments, the first RF power generator 127 operates in a power range between about 200 W and about 3000 W, and generates an RF signal with a frequency between about 13.56 MHz and about 60 MHz. In some embodiments, a matching network is disposed between the first RF power generator 127 and the RF antenna 121. In other embodiments, the plasma source 125 may comprise a remote plasma source configured to generate a plasma within an upstream plasma generation chamber and to subsequently provide the plasma to the processing chamber 102.

Further, the semiconductor processing system 100 comprises a lower electrode RF power generator 128 coupled to the lower electrode 108. The lower electrode RF power generator 128 comprises a switching element configured to switch between a first terminal having a first electric potential (e.g., about negative 600 V) and a second terminal having a second electric potential (e.g., about0 V). In some embodiments, the first terminal is also coupled to an RF signal generator. The lower electrode RF power generator is configured to provide a RF signal to the lower electrode 108 to increase the efficiency of the semiconductor processing system 100 (e.g., by maintaining control over a plasma sheath of the plasma). In some embodiments, the lower electrode RF power generator 128 operates in a power range between about 200 W and about 3000 W, and generates an RF signal with a frequency between about 400 kHZ and about 13.56 MHz.

In some embodiments, the lower electrode RF power generator 128 also provides signals to an electrostatic chuck electrode (not shown) disposed within the electrostatic chuck 110. In other embodiments, a separate electrostatic chuck power generator 130 is configured to apply a voltage to the electrostatic chuck electrode (not shown). In yet other embodiments, a second RF power generator 132 comprises the electrostatic chuck power generator 130 and the lower electrode RF power generator 128.

Moreover, the semiconductor processing system 100 comprises a first sidewall voltage generator 134 coupled to a first sidewall electrode 136, and a second sidewall voltage generator 138 coupled to a second sidewall electrode 140. In some embodiments, the first sidewall voltage generate 134 and the second sidewall voltage generate 138 may be a same voltage generator. The first sidewall electrode 136 and the second sidewall electrode 140 comprise an electrical conducting material. In some embodiments, the first sidewall electrode 136 is the first processing chamber sidewall 104 and the second sidewall electrode 140 is the second processing chamber sidewall 106. In other embodiments, the first sidewall electrode 136 is arranged behind the first processing chamber sidewall 104 and the second sidewall electrode 140 is arranged behind the second processing chamber sidewall 106. The first sidewall voltage generator 134 and the second sidewall voltage generator 138 are configured to apply a voltage to the first processing chamber sidewall 104 and the second processing chamber sidewall 106, respectively. In some embodiments, the first sidewall voltage generator 134 and the second sidewall voltage generator 138 may generate a negative AC bias voltage.

By using the first sidewall voltage generator 134 and the second sidewall voltage generator 138 to apply a voltage to the processing chamber sidewalls 104/106, a velocity at which gas particles within the processing chamber are attracted to the processing chamber sidewalls 104/106 is increased. The increased velocity of the gas particles causes the gas particles to bombard a by-product that has collected on the processing chamber sidewalls 104/106 with a sufficient energy to dislodge the by-product from the processing chamber sidewalls 104/106. Once dislodged, the by-product can be evacuated from the processing chamber 102 through the processing chamber gas outlet 124, thereby decreasing contamination of subsequently processed substrates within the processing chamber 102.

With reference to FIG. 2, a series of views of some more detailed embodiments of a semiconductor processing system 100 capable of implementing a method of the present disclosure for removing by-product that has accumulated on sidewalls of a processing chamber is provided. FIGS. 2A illustrates a cross-sectional view of a more detailed embodiments of a semiconductor processing system capable of implementing a method of the present disclosure. FIG. 2B illustrates a top view of a more detailed embodiments of a semiconductor processing system capable of implementing a method of the present disclosure.

As illustrated by the views of FIGS. 2A-2B, both the first RF power generator 127 and the second RF power generator 132 may further comprise a switching element 204 and a RF signal generator 202. The switching element 204 of the first RF power generator 127 is disposed between the RF signal generator 202 and the RF antenna 121. In some embodiments, the switching element 204 of the first RF power generator 127 is configured to open and close a circuit connecting the RF signal generator 202 to the RF antenna 121. In other embodiments, the switching element 204 of the first RF power generator 127 is configured to switch between a first terminal connected to the RF signal generator 202 and a second terminal connected to ground. The switching element 204 of the second RF power generator 132 is disposed between the RF signal generator 202 and the lower electrode 108. The lower electrode 108 is configured to receive a first electric potential (e.g., about negative 600 volts (V)) and a second electric potential (e.g., about 0 V). The switching element 204 of the second RF power generator 132 is configured to switch between a first terminal having a first electric potential (e.g., about negative 600 V) and a second terminal having a second electric potential (e.g., about 0 V). In some embodiments, the first terminal is also coupled to an RF signal generator 202.

The first processing chamber sidewall 104 may be a single continuous piece of conductive material that has a cylindrical shape. In some embodiments, the first sidewall electrode 136 may be a single continuous piece of conductive material having a cylindrical shape that surrounds the first processing chamber sidewall 104. In some such embodiments, the first sidewall voltage generator 134 may be connected to the first sidewall electrode 136 and configured to provide a voltage to the entire first sidewall electrode 136. In some alternative embodiments, a plurality of separate sidewall electrodes may surround the first processing chamber sidewall 104. In some such embodiments, the separate sidewall electrodes may be coupled to different sidewall voltage generators (e.g., a first sidewall electrode may be coupled to a first sidewall voltage generator and a second sidewall electrode may be coupled to a second sidewall voltage generator).

The first sidewall voltage generator 134 may comprise a switching element 204 configured to switch between a first terminal having a first electric potential (e.g., about negative 600 V) and a second terminal having a second electric potential (e.g., about 0 V). In some embodiments, the first terminal is also coupled to a DC bias voltage generator 206. In some embodiments, the DC bias voltage generator 206 is an AC bias voltage generator. The switching element 204 of the first sidewall voltage generator 134 is disposed between the DC bias voltage generator 206 and a first sidewall electrode 136. The switching element 204 is configured to switch between a first terminal connected to the DC bias voltage generator 206 and a second terminal connected to ground. In some embodiments, the DC bias voltage generator 206 outputs a negative voltage in a range of about 0.1 V to about 600 V. Although not illustrated in FIGS. 2A-2B, it will be appreciated that the second sidewall voltage generator 138 may also comprises a switching element 204 and a DC bias voltage generator 206

Moreover, in some embodiments, the semiconductor processing system 100 comprises a heating element 208 to control the temperature inside the processing chamber 102. In some embodiments, the heating element 208 is the processing chamber sidewalls 104/106.

With reference to FIGS. 3A-3G, a series of views of some embodiments of a method for removing by-product that has accumulated on sidewalls of a processing chamber is provided.

As illustrated by FIG. 3A, a semiconductor processing system 100 is provided. The semiconductor processing system 100 is pumping down a pressure of a processing chamber 102 in preparation of performing an etching process on a workpiece 114. In some embodiments, the pressure in the processing chamber 102 is controlled between 20 millitorr (mT) and 100 mT. The workpiece 114 is arranged on an electrostatic chuck 110 inside the processing chamber 102. In some embodiments, the workpiece 114 comprises a photoresist layer 120 disposed over a metal layer 118 that is disposed over a substrate 116.

Further, a valve of the processing chamber gas outlet 124 is open while a valve of the processing gas inlet 122 is closed. A vacuum pump (not shown) may be connected downstream from the valve of the processing chamber gas outlet 124. The vacuum pump is configured to pump gas out of the processing chamber 102 to lower the pressure of the processing chamber 102. In some embodiments, the semiconductor processing system 100 performs a purging step to remove unwanted gas molecules from the processing chamber 102 prior to pumping down the pressure of the processing chamber 102.

As the pressure of the processing chamber is pumped down, the switching element 204 disposed in the first RF power generator 127 may open a circuit between the RF antenna 121 and the RF signal generator 202 of the first RF power generator 127. Further, the switching element 204 of the second RF power generator 132 may connect the lower electrode 108 to ground. Also, the switching element 204 of the first sidewall voltage generator 134 connects the first sidewall electrode 136 to ground. In addition, the switching element 204 of the second sidewall voltage generator 138 connects the second sidewall electrode 140 to ground.

As illustrated by FIG. 3B, the workpiece 114 is being etched by an etching plasma 302. In some embodiments, the etching plasma 302 is formed by flowing an etching gas 304 into the processing chamber 102 and applying an RF signal to ignite the etching plasma 302. For example, the valve of the processing gas inlet 122 may open and allow the etching gas 304 to flow into the processing chamber 102. After the etching gas 304 has flowed into the processing chamber 102, the switching element 204 of the first RF power generator 127 closes the circuit between the RF signal generator 202 of the first RF power generator 127 and the RF antenna 121. In some embodiments, the first RF power generator 127 operates in a power range between about 200 W and about 3000 W, and generates an RF signal with a frequency between about 13.56 MHz and about 60 MHz. In some embodiments, the switching element 204 of the second RF power generator 132 also switches such that the RF signal generator 202 of the second RF power generator 132 is connected to the lower electrode 108. In some embodiments, the second RF power generator 132 operates in a power range between about 200 W and about 3000 W, and generates an RF signal with a frequency between about 400 k MHz and about 13.56 MHz. Accordingly, the RF signals output by the RF antenna 121 and the lower electrode 108 form the etching plasma 302, such that the workpiece 114 can be etched.

In some embodiments, the etching plasma 302 etches away portions of a metal layer 118. As the etching plasma 302 etches away portions of the metal layer 118, a large amount of by-product 210 is generated and accumulates on the processing chamber sidewalls 104/106. In some embodiments, the by-product 210 may be a non-volatile by-product, such as, copper, silver, gold, or some other non-volatile by-product. Therefore, as the workpiece 114 (or subsequent workpieces) continues to be etched, the etching plasma 302 will break some of the bonds of the non-volatile by-product 310 disposed on the processing chamber sidewalls 104/106 causing atoms of the non-volatile by-product to dislodged from the sidewalls. Accordingly, atoms of the non-volatile by-product 310 may accumulate as contaminants on the workpiece 114 disposed inside the processing chamber 102, which may result in a faulty workpiece.

As illustrated by FIG. 3C, the workpiece 114 has been removed from the processing chamber 102, and the pressure of the processing chamber 102 is being pumped down in preparation of cleaning the non-volatile by-product 310 from the processing chamber sidewalls 104/106. In some embodiments, because the workpiece 114 is removed from the processing chamber 102 and the cleaning process is not a wet cleaning process, the cleaning process to remove the non-volatile by-product 310 from the processing chamber sidewalls 104/106 is referred to as a waferless auto-clean (WAC) process. In some embodiments, the pressure of the processing chamber 102 is lowered to a range of about 40 millitorr (mT) to about 80 mT. In yet further embodiments, a heating element (not shown) heats the contents of the processing chamber 102 to a range of about 20° C. to about 80° C.

In some embodiments, during the pumping down phase of the cleaning process, the switching element 204 of the first RF power generator 127 opens the circuit between the RF signal generator 202 of the first RF power generator 127 and the RF antenna 121. Further, the switching element 204 of the second RF power generator 132 switches such that the lower electrode 108 is connected to ground. Moreover, the switching elements 204 of the first sidewall voltage generator 134 and the second sidewall voltage generator 138 connect the first sidewall electrode 136 and the second sidewall electrode 140 to ground, respectively.

As illustrated by FIG. 3D, the non-volatile by-product 310 disposed on the second processing chamber sidewall 106 is being cleaned from the second processing chamber sidewall 106. In some embodiments, the cleaning plasma 216 is formed inside the processing chamber 102 by flowing a processing gas 126 into the processing chamber 102 and igniting the plasma via RF signals. In some embodiments, the processing gas 126 may comprise, for example, oxygen, chlorine, boron, nitrogen, hydrogen, or a combination of the foregoing. For example, the valve of the processing gas inlet 122 may open and allow the processing gas 126 to flow into the processing chamber 102. After the processing gas 126 has flowed into the processing chamber 102, the switching element 204 of the first RF power generator 127 closes the circuit between the RF signal generator 202 of the first RF power generator 127 and the RF antenna 121, such that the RF antenna 121 outputs RF signals.

Unlike during the etching process depicted in FIG. 3B, the switching element 204 of the second RF power generator 132 connects the lower electrode 108 to ground in order to protect the electrostatic chuck 110 during the cleaning process. Rather, the switching element 204 of the second sidewall voltage generator 138 switches such that the second sidewall electrode 140 is connected to the DC bias voltage generator 206 of the second sidewall voltage generator 138. In some embodiments, the second sidewall electrode 140 may be connected to the DC bias voltage generator 206 for a time period in a range of about 400 seconds to about 600 seconds. In other embodiments, the second sidewall electrode 140 may be connected to the DC bias voltage generator 206 for a time period in a range of about 200 seconds to about 400 seconds. By connecting the second sidewall electrode 140 to the DC bias voltage generator 206 of the second sidewall voltage generator 138, the non-volatile by-product 310 disposed on the second processing chamber sidewall 106 is effectively cleaned due to the voltage potential between the cleaning plasma 216 and the second sidewall electrode 140 inducing physical bombardment (e.g., ion bombardment) of the non-volatile by-product 310.

As illustrated by FIG. 3E, after the non-volatile by-product 310 has been effectively bombarded to remove the non-volatile by-product 310 disposed on the second processing chamber sidewall 106, the processing gas 126 and the non-volatile by-product 310 is evacuated out of the processing chamber 102 via the processing chamber gas outlet 124. In some embodiments, during evacuation of the processing gas 126 and non-volatile by-product 310, the switching element 204 of the first RF power generator 127 disconnects the RF antenna 121 from the RF signal generator 202 of the first RF power generator 127. Further, the switching element 204 of the second sidewall voltage generator 138 switches to connect the second sidewall electrode 140 to ground. In some embodiments, the valve of the processing chamber gas outlet 124 remains open after the processing gas 126 has been evacuated to pump down the pressure of the processing chamber 102 for a subsequent process.

As illustrated by FIG. 3F, the non-volatile by-product 310 disposed on the first processing chamber sidewall 104 is being cleaned from the first processing chamber sidewall 104. In some embodiments, the cleaning plasma 216 is formed inside the processing chamber 102 by flowing a processing gas 126 into the processing chamber 102 and igniting the plasma via RF signals. In some embodiments, the processing gas 126 may comprise, for example, oxygen, chlorine, boron, nitrogen, hydrogen, or a combination of the foregoing. For example, the valve of the processing gas inlet 122 may open and allow the processing gas 126 to flow into the processing chamber 102. After the processing gas 126 has flowed into the processing chamber 102, the switching element 204 of the first RF power generator 127 closes the circuit between the RF signal generator 202 of the first RF power generator 127 and the RF antenna 121.

Unlike during the etching process depicted in FIG. 3B, the switching element 204 of the second RF power generator 132 connects the lower electrode 108 to ground in order to protect the electrostatic chuck 110 during the cleaning process. Rather, the switching element 204 of the first sidewall voltage generator 134 switches such that the first sidewall electrode 136 is connected to the DC bias voltage generator 206 of the first sidewall voltage generator 134. In some embodiments, the first sidewall electrode 136 may be connected to the DC bias voltage generator 206 for a time period in a range of about 400 seconds to about 600 seconds. In other embodiments, the first sidewall electrode 136 may be connected to the DC bias voltage generator 206 for a time period in a range of about 200 seconds to about 400 seconds. By connecting the first sidewall electrode 136 to the DC bias voltage generator 206 of the first sidewall voltage generator 134, the non-volatile by-product 310 disposed on the first processing chamber sidewall 104 is effectively cleaned due to the voltage potential between the cleaning plasma 216 and the first sidewall electrode 136 inducing physical bombardment (e.g., ion bombardment) of the non-volatile by-product 310.

As illustrated by FIG. 3G, after the non-volatile by-product 310 has been effectively bombarded to remove the non-volatile by-product 310 disposed on the first processing chamber sidewall 104, the processing gas 126 and the non-volatile by-product 310 is evacuated out of the processing chamber 102 via the processing chamber gas outlet 124. In some embodiments, during evacuation of the processing gas 126 and non-volatile by-product 310, the switching element 204 of the first RF power generator 127 disconnects the RF antenna 121 from the RF signal generator 202 of the first RF power generator 127. Further, the switching element 204 of the first sidewall voltage generator 134 switches to connect the first sidewall electrode 136 to ground. In some embodiments, the valve of the processing chamber gas outlet 124 remains open after the processing gas 126 has been evacuated to pump down the pressure of the processing chamber 102 for a subsequent process.

With reference to FIGS. 4A-4B, a series of views of some more embodiments of a method for removing by-product that has accumulated on sidewalls of a processing chamber is provided.

As illustrated by FIG. 4A, the semiconductor processing system 100 comprises a power switching manifold 402. In some embodiments, the power switching manifold 402 comprises the second RF power generator 132, the first sidewall voltage generator 134, and the second sidewall voltage generator 138 and controls their respective switching elements 204. In further embodiments, the power switching manifold 402 comprises a plurality of switches configured to switch between a first electric potential node, a second electric potential node, and/or a RF signal generator node, such that the power switching manifold controls the node connections to the lower electrode 108, electrostatic chuck 110, the first sidewall electrode 136, and the second sidewall electrode 140. In some embodiments, the second electric potential is larger than the first electric potential. For example, the first electric potential is about 0 V and the second electric potential is about negative 600 V.

As further illustrated by FIG. 4A, the non-volatile by-product 310 disposed on the first processing chamber sidewall 104 is being cleaned from the first processing chamber sidewall 104 at the same time the non-volatile by-product 310 disposed on the second processing chamber sidewall 106 is being cleaned from the second processing chamber sidewall 106. Similar to the cleaning process depicted in FIGS. 3D and 3F, the power switching manifold 402 switches the switching element 204 of the second RF power generator 132 to connect the lower electrode 108 to ground in order to protect the electrostatic chuck 110 during the cleaning process. However, unlike the cleaning process depicted in FIGS. 3D and 3F, the power switching manifold 402 switches the switching elements 204 of both the first sidewall voltage generator 134 and the second sidewall voltage generator 138 to connect them to their respective DC bias voltage generator 206. Accordingly, in some embodiments, the non-volatile by-product 310 disposed on both the first processing chamber sidewall 104 and the second processing chamber sidewall 106 can be effectively cleaned at the same time by inducing physical bombardment (e.g., ion bombardment) of the non-volatile by-product 310.

As illustrated by FIG. 4B, after the non-volatile by-product 310 has been effectively bombarded to remove the non-volatile by-product 310 disposed on both the first processing chamber sidewall 104 and the second processing chamber sidewall 106, the processing gas 126 and the non-volatile by-product 310 is evacuated out of the processing chamber 102 via the processing chamber gas outlet 124. In some embodiments, during evacuation of the processing gas 126 and non-volatile by-product 310, the power switching manifold 402 switches the switching element 204 of the first RF power generator 127 to disconnect the RF antenna 121 from the RF signal generator 202 of the first RF power generator 127. Further, the power switching manifold 402 switches the switching elements 204 of both the first sidewall voltage generator 134 and the second sidewall voltage generator 138 from their respective first terminal to their respective second terminal, which connects both the first sidewall electrode 136 and the second sidewall electrode 140 to ground.

With reference to FIG. 5, a flowchart 500 of some embodiments of the method for removing by-product that has accumulated on sidewalls of a processing chamber is provided. While the disclosed method and other methods illustrated and/or described herein may be illustrated and/or described herein as a series of acts or events, it will be appreciated that the illustrated ordering of such acts or events are not to be interpreted in a limiting sense. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein. Further, not all illustrated acts may be required to implement one or more aspects or embodiments of the description herein, and one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases.

At 502, the pressure of a processing chamber that has a workpiece disposed within is pumped down. An example of act 502 can be seen with reference to previously illustrated FIG. 3A.

At 504, the workpiece disposed within the processing chamber is processed, which may result in by-product accumulating on sidewalls of the processing chamber. An example of act 504 can be seen with reference to previously illustrated FIG. 3B.

At 506, the processed workpiece is removed from the processing chamber. An example of act 506 can be seen with reference to previously illustrated FIG. 3C.

At 508, the pressure of the processing chamber is pumped down. An example of act 508 can be seen with reference to previously illustrated FIG. 3C.

At 510, a cleaning plasma is generated inside the processing chamber from a processing gas by applying a radio frequency (RF) signal to a RF antenna. An example of act 510 can be seen with reference to previously illustrated FIG. 3D.

At 512, a lower electrode is connected to a first electric potential. An example of act 512 can be seen with reference to previously illustrated FIG. 3D.

At 514, a bias voltage having a second electric potential that has a greater magnitude than the first electric potential is applied to a sidewall electrode to induce ion bombardment of the by-product disposed on the sidewalls of the processing chamber. An example of act 514 can be seen with reference to previously illustrated FIG. 3D.

At 516, the processing gas and the by-product are evacuated from the processing chamber. An example of act 516 can be seen with reference to previously illustrated FIG. 3E.

Thus, as can be appreciated from above, the present disclosure relates to an improved method (and related apparatus) for removing by-product that has accumulated on semiconductor processing chamber sidewalls.

Accordingly, in some embodiments, the present application provides a method for cleaning a processing chamber. The method includes introducing a processing a gas into a processing chamber that has a by-product disposed along sidewalls of the processing chamber. A plasma is generated from the processing gas using a radio frequency (RF) signal. A lower electrode is connected to a first electric potential. Concurrently, a bias voltage having a second electric potential is applied to a sidewall electrode to induce ion bombardment of the by-product, in which the second electric potential has a larger magnitude than the first electric potential. The processing gas is then evacuated from the processing chamber.

In other embodiments, the present application provides a plasma processing apparatus. The plasma processing apparatus includes a processing chamber comprising a lower electrode arranged below an upper surface of an electrostatic chuck configured to receive a workpiece and between sidewalls of the processing chamber. A first radio frequency (RF) power generator is electrically connected to a RF antenna. A sidewall voltage generator is electrically connected to a sidewall electrode. A second RF power generator is electrically connected to the lower electrode.

In yet other embodiments, the present application provides a method for cleaning a processing chamber. The method includes connecting a switching element of a sidewall voltage generator to a first electric potential, thereby connecting a sidewall electrode to the first electric potential. A switching element of a second radio frequency (RF) power generator is switched to a second electric potential, thereby connecting a lower electrode to the second electric potential. A substrate comprising a first material is processed inside a processing chamber, in which the process generates by-product comprising the first material that adheres to a sidewall of the processing chamber. The processed substrate is removed from the processing chamber. A processing gas is introduced into the processing chamber. The switching element of the second RF power generator is switched to the first electric potential, and concurrently the switching element of the sidewall voltage generator is switched to a third electric potential. A cleaning plasma is generated inside the processing chamber by connecting a first RF power generator to a RF antenna. The processing gas and the by-product are then evacuated from the processing chamber.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A method for cleaning a processing chamber, the method comprising: introducing a processing gas into a processing chamber having a by-product disposed along sidewalls of the processing chamber; generating a plasma from the processing gas using a radio frequency (RF) signal; connecting a lower electrode that is disposed within the sidewalls of the processing chamber to a first electric potential; concurrently applying a bias voltage having a second electric potential to a sidewall electrode to induce ion bombardment of the by-product, wherein the second electric potential has a larger magnitude than the first electric potential; and evacuating the processing gas from the processing chamber.
 2. The method of claim 1, further comprising: etching a workpiece using an etching plasma, wherein a material dislodged from the workpiece by the etching plasma attaches to the sidewall of the processing chamber to form the by-product; and removing the workpiece from the processing chamber prior to introducing the processing gas into the processing chamber.
 3. The method of claim 1, wherein the processing gas comprises chlorine or oxygen.
 4. The method of claim 1, wherein the first electric potential is substantially equal to ground, and wherein the second electric potential is between about 0 Volts (V) and about negative 600 V.
 5. The method of claim 1, wherein the by-product comprises an inert metal.
 6. The method of claim 1, wherein bias voltage is applied to the sidewall electrode for about 200 seconds to about 600 seconds.
 7. A plasma processing apparatus, comprising: a processing chamber comprising a lower electrode arranged below an upper surface of an electrostatic chuck configured to receive a workpiece and between sidewalls of the processing chamber; a first radio frequency (RF) power generator electrically connected to a RF antenna; a sidewall voltage generator electrically connected to a sidewall electrode; and a second RF power generator electrically connected to the lower electrode.
 8. The plasma processing apparatus of claim 7, wherein the sidewall electrode is a sidewall of the processing chamber.
 9. The plasma processing apparatus of claim 7, wherein the sidewall voltage generator is configured to apply a DC bias voltage to the sidewall electrode to induce ion bombardment of a non-volatile by-product disposed on a sidewall of the processing chamber.
 10. The plasma processing apparatus of claim 7, wherein the sidewall voltage generator comprises a switching element having a first terminal connected to a first electric potential and a second terminal connected to a voltage generator.
 11. The plasma processing apparatus of claim 10, wherein the sidewall electrode is separated from the electrostatic chuck by a sidewall of the processing chamber.
 12. The plasma processing apparatus of claim 11, wherein the second RF power generator comprises a switching element having a first terminal connected to the first potential and a second terminal connected to a RF signal generator.
 13. A method for cleaning a processing chamber, the method comprising: connecting a switching element of a sidewall voltage generator to a first electric potential, thereby connecting a sidewall electrode to the first electric potential; connecting a switching element of a second radio frequency (RF) power generator to a second electric potential, thereby connecting a lower electrode to the second electric potential; processing a substrate comprising a first material inside a processing chamber, wherein the process generates a by-product comprising the first material that adheres to a sidewall of the processing chamber; removing the processed substrate from the processing chamber; introducing a processing gas into the processing chamber; switching the switching element of the second RF power generator to the first electric potential and concurrently switching the switching element of the sidewall voltage generator to a third electric potential; generating a cleaning plasma inside the processing chamber by connecting a first RF power generator to a RF antenna; and evacuating the processing gas and the by-product from the processing chamber.
 14. The method of claim 13, wherein the switching element of the sidewall voltage generator being connected to the third electric potential induces ions of the cleaning plasma to bombard the by-product.
 15. The method of claim 13, wherein the processing gas is introduced after the processed substrate is removed from the processing chamber.
 16. The method of claim 13, wherein the second electric potential and the third electric potential each have a greater magnitude than the first electric potential.
 17. The method of claim 16, wherein the first electric potential is substantially equal to ground, wherein the second electric potential is between about 0 Volts (V) and about negative 600 V, and wherein the third electric potential is between about 0 V and about negative 600 V.
 18. The method of claim 17, wherein the first material comprises an inert metal.
 19. The method of claim 18, wherein the switching element of the sidewall voltage generator is connected to the third electric potential for about 200 seconds to about 600 seconds so as to enable the processing gas to dislodge the by-product from the sidewall of the processing chamber.
 20. The method of claim 19, wherein the sidewall electrode continuously extends around a perimeter of the processing chamber. 